7. Transport In Plants

Question 2

water role

Answer 2

some mineral ions and organic compounds can be transported within plants dissolved in water

Question 3

describe the transport of water from the soil to the xylem

Answer 3

• apoplast pathway, including reference to lignin and cellulose.
• symplast pathway, including reference to the endodermis, Casparian strip and suberin.

Question 4

transpiration process

Answer 4

transpiration involves the evaporation of water
from the internal surfaces of leaves followed by diffusion of water VAPOUR to the atmosphere

Question 5

movement of water in the xylem

Answer 5

hydrogen bonding of water molecules is involved with movement of water in the xylem by cohesion-tension in
transpiration pull and by adhesion to cellulose in cell walls.

Question 6

xerophytic plants

Answer 6

adapted to reduce water loss by transpiration. reduce diffusion of water VAPOUR out via the stomata

thick waxy cuticle- increase waterproof layer for increased diffusion distance.

sunken stoma- decrease water potential as humid air collects near external environment.

trichomes-
spikes-

Question 7

translocation

Answer 7

assimilates dissolved in water, such as sucrose and amino acids, move from sources to sinks in phloem sieve tubes

Question 8

companion cells transfer assimilates to phloem sieve tubes

Answer 8

companion cells transfer assimilates to phloem sieve tubes, with reference to proton pumps and cotransporter proteins.

1 protons, moved by active transport / pumped, out of (companion) cell ;
A using, energy / ATP for active transport
2 protons, moved into / enter / AW, cell wall / apoplast ;
R if moved out to phloem sieve tube
3 proton gradient builds up in, apoplast / cell wall ;
A higher concentration
A high concentration if mp4 gained
4 protons move back (into companion cell), by facilitated diffusion / AW ;
e.g. down, electrochemical / concentration, gradient
from high(er) to low(er) concentration
A diffuse if movement is described through a transport protein in mp5
5 protons cotransport amino acids
or
amino acids move with protons through, a cotransporter / a cotransport protein / (amino acid) transporter ;
6 amino acids, transported / AW, against their concentration gradient ;

Question 9

explain mass flow in phloem sieve tubes

Answer 9

explain mass flow in phloem sieve tubes down a hydrostatic pressure gradient from source to sink.